MPI Datatypes

• The data in a message to sent or received is described by a triple (address, count, datatype), where

• An MPI datatype is recursively defined as:

  • predefined, corresponding to a data type from the language (e.g., MPI_INT, MPI_DOUBLE_PRECISION)
  • a contiguous array of MPI datatypes
  • a strided block of datatypes
  • an indexed array of blocks of datatypes
  • an arbitrary structure of datatypes

• There are MPI functions to construct custom datatypes, such an array of (int, float) pairs, or a row of a matrix stored columnwise.

Notes: